This invention relates to a process for the pyrolysis of waste materials having halogen-containing, sulphur-containing and/or heavy-metal-containing constituents, the waste materials being subjected to carbonization in a low-temperature carbonization zone at temperature in the range from 300.degree. to 600.degree. C.
The pyrolysis of waste materials having halogen-containing constituents (for example waste materials containing PVC and/or fluorine-containing polymers) is accompanied by the formation of hydrohalic acids (HF, HCl) which cause considerable problems in regard to gas and effluent purification and which necessitate the use of expensive materials for the construction of the low-temperature carbonization zone and the following gas purification line. In the pyrolysis of sulphur-containing waste materials, the presence of H.sub.2 S and SO.sub.2 in the pyrolysis gas gives rise to similar problems.
In this connection, it has to be borne in mind that, under laws governing the incineration of refuse, insofar as it involves the emission of chlorine, fluorine and SO.sub.2 for example, the inorganic chlorine compounds (expressed as Cl.sup.-), fluorine compounds (expressed as F.sup.-) and SO.sub.2 in the exhaust gas of installations with a waste throughput of more than 0.75 t/h should not exceed levels of 100 mg/Nm.sup.3, 5 mg/Nm.sup.3 and 80 mg/Nm.sup.3, respectively. The maintenance of these levels involves heavy equipment cost for the gas and effluent purification of the pyrolysis gases formed during the pyrolysis of waste materials having halogen-containing, sulphur-containing and/or heavy-metal-containing consituents.